Madagascar Periwinkle — Safety & Interactions
Chang Chun Hua · Herba Catharanthi Rosei
Contraindicated / High risk. Use only under practitioner supervision.
Contraindications
- Unsupervised self-medication for any indication — HIGH RISK; alkaloid content requires controlled dosing
- Pregnancy — embryotoxic and teratogenic; vinca alkaloids are Pregnancy Category D
- Peripheral neuropathy (pre-existing) — vinca alkaloids worsen neuropathy
- Concurrent chemotherapy without oncology supervision
Cautions
- SAFETY-CRITICAL: The whole plant contains vinca alkaloids at pharmacologically active concentrations. Unlike most TCM herbs, C. roseus is NOT suitable for casual folk self-treatment — therapeutic doses overlap with toxic doses
- Neurotoxicity: peripheral neuropathy (sensory, motor, autonomic) is the primary dose-limiting toxicity of vinca alkaloids; reported even at sub-pharmaceutical doses with repeated exposure
- SIADH risk: vinca alkaloids are associated with syndrome of inappropriate ADH secretion — hyponatremia reported
- Hepatotoxicity: case reports of liver injury following unsupervised ingestion of plant preparations
- Folk hypoglycemic use: if used, monitor blood glucose closely; additive effect with antidiabetic drugs
- Standard folk dose (Chinese practice): 5–15g decoction — but this dose range carries unpredictable alkaloid delivery and is NOT recommended without medical supervision
Drug Interactions
| Drug Class / Substrate | Mechanism | Severity | Source |
|---|---|---|---|
| Antineoplastic vinca alkaloids (vincristine, vinblastine, vinorelbine): additive toxicity — peripheral neuropathy, myelosuppression, SIADH; do not combine plant with pharmaceutical vinca alkaloids | |||
| Antidiabetic drugs (insulin, metformin, sulfonylureas): additive hypoglycemic effect via serpentine; monitor blood glucose | |||
| Antihypertensive drugs: additive blood pressure-lowering effect via ajmalicine; monitor for hypotension | |||
| CYP3A4 substrates: vinca alkaloids are CYP3A4 substrates and inhibitors; potential for complex bidirectional interactions with CYP3A4-metabolised medications | |||
| Neurotoxic drugs (platinum compounds, taxanes, thalidomide): additive peripheral neuropathy risk | |||
Pregnancy
Not recommended during pregnancy. Consult a qualified practitioner before any use.
This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before using herbal medicines, especially if you take prescription medications.